Fair Value Measurements - Nonrecurring (Details) $ in Millions	Jun. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held for sale	$ 1,502.6	$ 1,072.0
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held for sale	0.0	0.0
Other mortgage loans	0.0	0.0
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Inventories [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventories	0.0	0.0
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held for sale	4.2	2.7
Other mortgage loans	2.8	1.8
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Inventories [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Inventories	0.0	4.5
Home Building [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held for sale	$ 0.0	$ 0.0
Measurement Input, Discount Rate [Member] \| Inventories [Member] \| Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Real Estate Owned, Measurement Input	0.16
Measurement Input, Discount Rate [Member] \| Inventories [Member] \| Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Real Estate Owned, Measurement Input	0.18

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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No definition available.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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Amount, after valuation allowance, of financing receivable held for sale and not part of disposal group. Excludes loan covered under loss sharing agreement and loan classified as investment in debt security.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-Topic 310
-SubTopic 10
-Section 45
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-URI http://asc.fasb.org/extlink&oid=121593590&loc=d3e4428-111522

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Value of input used to measure real estate owned by financial institution by financial institution which is not directly related to its business.

+ References

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